Goodwill and Other Intangible Assets - Additional Information (Details) - USD ($) $ in Thousands	May 31, 2018	Aug. 31, 2017
Impaired Assets [Line Items]
Goodwill	$ 538,792	$ 530,081
Future Amortization Expense, Remainder of 2018	5,100
Future Amortization Expense, 2019	20,000
Future Amortization Expense, 2020	19,300
Future Amortization Expense, 2021	18,400
Future Amortization Expense, 2022	16,400
Future Amortization Expense, 2023	13,400
Future Amortization Expense, Thereafter	$ 23,100